The Transport for London Bus Safety Standard: Visual Conspicuity

Document summary

Visual conspicuity is about making the bus more noticeable to other road users, particularly VRUs. This might help VRUs to detect the presence of a bus and the collision risk it represents if they were to cross in front of it. There are a variety of solutions available that might help, and Transport for London (TfL) is requesting innovative solutions to be evaluated. Test and assessment procedures will have to be developed for specific solutions that are selected in the future.

The assessment of the visual conspicuity solutions has required the development of a new evaluation procedure. This consists of a laboratory-based test reviewing photos of buses in a variety of conditions. This assesses the participants’ ability to search and recognise the bus in a London visual scene. A second phase of testing is track-based and assesses how well participants judge their ability to successfully cross in front of an approaching bus (by releasing the button, but not stepping out). These procedures were designed to assess the ‘looked but failed to see’ and ‘time to collision’ (or saw but misjudged the risk) errors respectively.

Within the regulatory requirements it is possible to add extra marker lights to buses. Additional reflective tape was also investigated, as well as the combination with both lights and tape. The idea is that by creating a rectangular frame of the shape of the bus front then VRUs might better identify and predict the speed of the bus as the rectangle enlarges whilst moving towards them. These conditions were tested against a baseline bus, but were not proved to be more effective for fully able people. However, TfL is considering whether these solutions could be effective for impaired persons, such as visually impaired or intoxicated people.